1. Field of the Invention
The present invention relates to a synchronizer ring in a synchronizer speed change gear having a round elastic ring.
2. Prior Art
The synchronizer ring of this type is developed by Honda Motor Co., Ltd. (Honda Synchronizer Ring) and is disclosed in Japanese Patent Publication No. 48-24096 and illustrated in FIG. 1. The synchronizer ring 1 includes a boss 2, projections 3, 3, 3 mounted on the surface of the boss 2 for the angular interval of 120.degree. and a round elastic ring 4 disposed over the projections 3, 3, 3.
An operation of the prior synchronizer ring having such arrangement will be described with reference to FIGS. 2A to 2D.
In FIG. 2A, when a sleeve 5 contacts the round elastic ring 4 at the time of shifting operation of the synchronizer ring 1, the round elastic ring 4 serves to absorb an impulse of the movement of the sleeve 5 toward a driven gear 7 and to push the synchronizer ring 1 to a driven gear 7 before a tooth 6 of the sleeve 5 contacts a tooth 8 of the synchronizer ring 1 to preliminarily rotate a driven gear 7.
In FIG. 2B, inasmuch as the tooth 8 of the synchronizer ring 1 prevents the tooth 6 of the sleeve 5 from entering inside the tooth 8 when the sleeve 5 starts to contact the tooth 8 of the synchronizer ring 1, the synchronizer ring 1 is forcibly pushed toward the driven gear 7 to effect the synchronized shifting operation. At this time, the round elastic ring 4 is deflected in maximum.
In FIG. 2C, the tooth 6 of the sleeve 5 passes the tooth 8 of the synchronizer ring 1 and starts to contact a tooth 10 of the driven gear 7 when the synchronized shifting operation is completed. No noise is generated when the tooth 6 contacts the gear 10 since the synchronized shifting operation is already completed so that the tooth 6 of the sleeve 5 smoothly enters inside the gear 10 of the driven gear 7.
It is evident from FIG. 2D that the tooth 6 of the sleeve 5 enters completely inside the tooth 10 of the driven gear 7 so that the driven gear 7 rotates together with the sleeve 5.
The prior art speed change gear employing the round elastic ring has a high performance characteristic irrespective of its simple structure. However, in the case the prior speed change gear is employed in a big truck, the diameter of the round elastic ring 4 becomes more than 90 mm. Inasmuch as the distance between each fulcrum point supporting the round elastic ring 4 becomes excessive in this case, an elastic force is less than a prescribed value even if the deflection strength is applied to the round elastic ring 4 so that the load to be generated is insufficient. That is, there are such problems the synchronizer ring can not achieve the function to absorb an impulse of the movement of the sleeve toward a driven gear and to push the synchronizer ring to a driven gear to preliminarily rotate a driven gear.
There is such a means to solve the problems that the cross section of the round elastic ring 4 (secondary moment of cross section) is enlarged. According to this means, the size and the weight of the round elastic ring 4 becomes excessive within a limited space of the speed change gear so that this means can not be effectively employed.